Table 2.

Proposed diagnostic criteria for microscopic polyangiitis (MPA). (Research Committee on Intractable Vasculitis and Research Committee on Epidemiology of Intractable Diseases, The Ministry of Health and Welfare of Japan, 1998).

(1) Clinical manifestations

(i) rapidly progressive glomerulonephritis

(ii) pulmonary hemorrhage or interstitial pneumonia

(iii) organ involvement besides kidney and lung:

purpura, subcutaneous bleeding, gastrointestinal bleeding, mononeuritis multiplex, and so forth

(2) Histological findings

necrotizing vasculitis in capillaries, venules, or arterioles, with perivascular inflammatory infiltrate

(3) Laboratory findings

(i) positive MPO-ANCA

(ii) elevated level of CRP

(iii) proteinuria and/or hematuria, or elevated levels of BUN and/or creatinine

(iv) chest X-ray findings: infiltration (pulmonary hemorrhage), and/or interstitial pneumonitis

(4) Diagnosis

(i) Definite

(a) At least two clinical manifestations with the histological findings

(b) At least two clinical manifestations including items (i) or (ii), and positive MPO-ANCA

(ii) Probable

(a) At least three clinical manifestations

(b) One clinical manifestation and positive MPO-ANCA

(5) Exclusion diseases

(i) polyarteritis nodosa

(ii) Wegener's granulomatosis

(iii) allergic granulomatous angiits (Churg-Strauss syndrome)

(iv) Goodpasture syndrome